First try to get enough rest and fluids before your trip, bring plenty of snacks- no-one wants to get hangry or deal with the hangry person on their trip, try to get the shortest travel day possible without making the connections too short. Yes, it may cost more but it is worth your sanity and your energy, don’t book basic economy if you can help it so you can choose your seat so you aren’t crammed in the middle seat.
I do my best to bring as many comforts of home as I can- I have a footrest hammock that takes the pressure off my hips and back, I bring a refillable water bottle with a carabiner clip to hang from the seatback pocket, I rarely turn down the drink service unless I’m trying to sleep, a comfortable neck pillow with a washable cover is essential, earplugs or noise-canceling headphones, sanitation wipes, and of course my bioscarf that filters, germs, bad smells, and allergens. https://www.g95.com/?rfsn=4108173.8ab118
I also bring Zicam nose swabs just in case I start feeling sick on the trip and make sure to stay hydrated and eat as healthy as I can. (Be sure to talk to your doctor for what is best for you). When I travel for work and know I am going to be on the go I try to add a couple of days at the end of the trip so I can recuperate before the long travel day home. I make sure to keep my medications and valuables close to me and keep my passport in a lanyard wallet around my neck so I’m not freaking out worried about finding it.
Things I have learned traveling with disabilities is to give yourself plenty of time so you aren’t stressed or rushed, don’t be afraid to ask for help at the airport, they have wonderful people that will take your from the check-in counter to your gate and have someone waiting for you when you deplane. If you need the service don’t be too proud to use it. Ask your doctor for a note to board early so you aren’t being bumped and banged into while trying to get to your seat.